GM Quad-4 engine

The Quad 4 (called Twin Cam after 1995) was a DOHC and SOHCstraight-4automobile engine produced by General Motors' Oldsmobile division. It was a modern engine for the time, but was criticized for roughness as well as its longevity. Balance shafts were added in 1995, also known as a transitional year from the Quad 4 to the renamed TWIN CAM variant, in 1996 2.4L (LD9) the complete engine makeover was accomplished. The name is derived from the engine's four cylinders and four valve per cylinder layout. There was a single overhead camshaft variant that was produced for a brief time. The Quad 4 used an iron block and an aluminum head.

The Quad 4 debuted in 1987 and was replaced after 2001 by the Ecotec. Quad 4 engines were produced at GM's Delta Engine Plant (Plant 5) in Delta Township, Michigan. In recent years, it has gained a minor following in hot rodding circles as a period style engine (which looks like a 1930's Offenhauser twin cam unit).

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Quad OHC

A SOHC variant of the Quad 4 was intended to replace the Tech IV. Debuting in 1992, this Quad OHC was an 8-valve engine and produced 120 hp (89 kW), 40 hp (30 kW) less than a Quad 4 from the same era. Torque was 140 ft·lbf (190 N·m).

Although power and economy were better than the pushrod Tech IV, the Quad OHC was retired after 1994 when the DOHC version became standard.

LD2

The LD2 was the standard version of the Quad 4. The LD2 was the first incarnation of the Quad 4. It is a lower output version of the Quad 4 when compared to the LGO or High Output Quad 4. There was a transitional version of the LD2 in 1995.

1995

For 1995, a balance shaft-equipped version of the 2.3 L version was produced. A clever arrangement ensured a constant load on the shafts: The crank drove one shaft, which drives the second, which drives the oil pump. The shafts spun at twice the engine rpm, forcing the redline to be reduced from 6800 to 6500 rpm. Output was 150 hp (110 kW) and 150 ft·lbf (200 N·m). This was the only Quad 4 family engine produced in 1995. This was known as a transitional year for the engine family.

LG0

The High-Output 2.3 L LG0 version produced 180 hp (134 kW) from 1989 to 1992, and 175 hp (130 kW) in 1993 and 1994. Changes included more aggressive camshafts, and an extra half point of compression (from 9.5:1 to 10.0:1).

LD9

The LD9Twin Cam was a 2.4 L (146 cu in) Quad 4 variant with balance shafts, debuting in 1996. Bore was decreased from 92 mm (3.6 in) to 90 mm (3.5 in) and stroke increased from 85 mm (3.3 in) to 94 mm (3.70 in) for better torque, and power was increased to 150 hp (112 kW).[1] This engine received a minor update halfway through the 1999 model year that eliminated the EGR, increased the compression ratio from 9.5:1 to 9.7:1, and switched from low impedance fuel injectors to high impedance.

note the LD9 has been know to have connecting rod and connecting rod bearing problems(they tend to throw rods) when they get over 100,000 miles on them. First you will start to knock with out warning, if you do experience this problem you have time to save your engine(rebuilding it or rebuild shop) Some say to use 5w-40, 10w-40 oil, or 20w-50 racing oil to help prevent this or buy aftermarket connecting rods and bearings(which are a lot stronger)